1. Field of the Invention
The present invention relates to a rotary operation type input device to be mounted on various electronic appliances and having an input operation unit for searching or entering various electronic data.
2. Background Art
Recently, a rotary operation type input device for selecting and establishing various items displayed on a screen of an electronic appliance is demanded to be smaller in thickness and lower in cost in the recent trend of electronic appliances of smaller size and higher density.
A conventional rotary operation type input device disclosed in Unexamined Japanese Patent Application Publication No. 2003-281972 is explained by referring to FIG. 7 and FIG. 8.
FIG. 7 is a sectional view of a conventional rotary operation type input device, and FIG. 8 is its perspective exploded view. In these drawings, a conventional rotary operation type input device has operation body 1 made of resin formed in a disk of circular ring shape having circular central hole 1A. Magnetic plate 2 of silicon steel plate or magnetic stainless steel processed and formed in a circular ring shape is fixed below operation body 1. Ring magnet 3 of circular shape is fixed beneath magnetic plate 2. That is, operation body 1, magnetic plate 2, and ring magnet 3 are overlaid and fixed concentrically.
Ring magnet 3 is magnetized alternately in N poles and S poles at specified angles in the circumferential direction. That is, in ring magnet 3 shown in FIG. 8, the hatching positions are N poles magnetized in a specified angle range, and the other positions are S poles magnetized in the same angle range.
In the conventional rotary operation type input device, the lower part of operation body 1 is provided with base 4 made of resin formed in a circular ring shape having circular through-hole 4A in the center, concentrically with operation body 1. Base 4 is formed with inner tube 4B protruding upward in the circumference of through-hole 4A, and has ring support part 4C protruding and formed upward concentrically across a gap at the outer circumferential side from inner tube 4B.
In operation body 1, as shown in FIG. 7, the inner circumference of defining protrusion 1B protruding downwardly in a circular ring shape is rotatably engaged with the outer circumference of inner tube 4B of base 4. Further in operation body 1, the outer circumferential lower side portion of operation body 1 is supported on ring support part 4C of base 4. At this time, ring magnet 3 integrated beneath operation body 1 is positioned in a ring-shaped space formed between inner tube 4B and ring support part 4C of base 4. Clearance hole 4D is formed in a specified angle range at the bottom position of ring-shaped space formed between inner tube 4B and ring support part 4C of base 4 (see FIG. 8).
Fixed magnet 5 for generating an operation contact sensation is fixed in a ring-shaped bottom portion formed between inner tube 4B and ring support part 4C of base 4. This fixed magnet 5, as shown in FIG. 8, is fixed only in part in the bottom portion, and the top side of fixed magnet 5 and the bottom side of ring magnet 3 are closely disposed opposite to each other across a specified gap in the vertical direction.
On wiring board 10, at a position corresponding to clearance hole 4D of base 4, detection element 11 such as an MR element or a Hall element for detecting changes in the intensity of a magnetic field is disposed. Also on wiring board 10, press-down switch 13 is disposed at a position corresponding to through-hole 4A provided in the center of base 4.
Insulating sheet 12 is disposed to as to cover wiring board 10 including detection element 11 and press-down switch 13. Above insulating sheet 12, base 4 is mounted so as to be engaged rotatably with operation body 1. Insulating sheet 12 is pressed down tightly on wiring board 10 at the lower end of leg part 20A protruding and formed beneath fixing member 20 constituted by the casing of an electronic appliance or the like. Insulating sheet 12 is pressed down at the outer edge of base 4 by inner step 20B provided in leg part 20A, and base 4 is positioned.
At a further inside upward position of inner step 20B, upper wall 20C is formed to protrude in a horizontal direction, and the peripheral portion of operation body 1 is assembled so as to be positioned beneath upper wall 20C. As a result, upward slipping of operation body 1 is prevented. The top side of operation body 1 at a position inwardly of upper wall 20C is provided with small, radial protrusions 1C for assisting operation.
The structure of press-down switch 13 is described. Press-down switch 13 has movable contact 14 of circular dome shape mounted on an outside fixed contact (not shown) provided on wiring board 10 at its outer circumferential end. Movable contact 14 is positioned and fixed on wiring board 10 by adhesive tape 17 disposed so as to cover the movable contact 14 from above. While press-down switch 13 is not operated, the central bottom side of movable contact 14 is disposed opposite across a specific gap a central fixed contact (not shown) disposed in wiring board 10. Adhesive tape 17 is covered with insulating sheet 12 as described above, and operation button 18 is mounted thereon for pressing movable contact 14 and is disposed movably in a vertical direction in through-hole 4A of base 4.
Operation button 18 has flange 18A protruding toward the outer circumferential side. While press-down switch 13 is not operated, the top side of flange 18A abuts against the bottom side of the inner edge composing circular central hole 1A of operation body 1, and upward slipping is prevented. The upper end of operation button 18 protrudes upward from circular central hole 1A.
The conventional rotary operation type input device is thus constituted, and its operation is as follows. The top side of operation body 1 of circular ring shape is touched by a finger or the like, and is rotated in a forward or reverse direction on a horizontal plane. By this rotating operation, operation body 1 rotates horizontally along the outer circumference of inner tube 4B of base 4 while being supported on ring support part 4C, and hence ring magnet 3 integrated with operation body 1 is rotated together with operation body 1.
Along with rotary movement of ring magnet 3, the distribution state of magnetic field fluctuates, and it is detected by detection element 11, and a specified output is obtained. By the output from detection element 11, the rotating direction and rotating amount of operation body 1 are judged. At the same time, one fixed magnet 5 for generating an operation contact sensation fixed to base 4 repeats attraction and repulsion with ring magnet 3, and this attraction and repulsion force is felt like a click contact sensation.
When operation button 18 disposed in the center of operation body 1 is pressed, the central position of movable contact 14 is pressed by the bottom convex part of operation button 18 by way of insulating sheet 12 and adhesive tape 17. When this pressing force exceeds a specified force, movable contact 14 is elastically inverted in the convex dome-like portion and the bottom side of the central part contacts with the central fixed contact, and hence the outside fixed contact and the central fixed contact electrically contact with each other, thereby turning on the switch.
When the pressing force of operation button 18 is removed, by the self-restoring force of movable contact 14, the dome-like portion returns to the original upward swollen state, and movable contact 14 is departed from the central fixed contact, thereby returning to the state shown in FIG. 7.
In the conventional rotary operation type input device, however, ring magnet 3 and fixed magnet 5 are disposed opposite to each other as mentioned above. Hence, the position to be mounted on insulating sheet 12, that is, the mechanical portion of operation body 1 combined with base 4 requires at least a specified clearance between ring magnet 3 and fixed magnet 5, and thus at least a specified vertical dimension to be laminated in the vertical direction. In such configuration, it is hard to meet the requirement of thin design of the entire device, and it is expensive because a plurality of magnets should be required.
In the conventional rotary operation type input device, moreover, ring magnet 3 is attracted and repelled to and from fixed magnet 5 in order to generate a click contact sensation. Although a clear click contact sensation is achieved by the attraction and repulsion force, operation body 1 moves up and down between ring support part 4C of base 4 and upper wall 20C of fixing member 20. Therefore, collision of operation body 1 against ring support part 4C or upper wall 20C is repeated, and an unusual sound is generated by such collision.